1. Field of the Invention
The present invention relates to an optical disc driver.
2. Description of the Related Art
Optical recording media for digitalizing a large amount of information to record or reproduce the digitalized information have been developed according as an information-oriented society has arrived. Among them, compact discs (CD) and digital versatile discs (DVD) are commonly used.
The information stored in the optical recording media can be reproduced using the optical disc drivers. The optical disc drivers repeatedly load the optical recording media in turntables and unload the optical recording media from turntables in order to record information in or to reproduce information from the optical recording media.
The optical disc drivers clamp the loaded optical recording media, for example, optical discs in the turntables and/or eject the loaded optical recording media, for example, optical discs from the turntables. That is, when the optical recording media are loaded on the turntables, the optical recording media are clamped while the recording or reproducing operation is performed. When information is recorded in or reproduced from the optical recording media, clamping is released and the optical recording media are unloaded from the turntables. The optical disc driver includes a spindle motor for rotating the turntable. A clamp plate for performing a clamping function is combined with the turntable.
FIGS. 1A and 1B schematically illustrate a related art clamp plate. FIGS. 2A and 2B schematically illustrate a related art turntable. FIG. 3 illustrates a state in which the clamp plate illustrated in FIGS. 1A and 1B and the turntable illustrated in FIGS. 2A and 2B are combined with each other.
As illustrated in FIGS. 1A and 1B, a related art clamp plate 10 is donut-shaped and a plurality of fastening holes 1 are formed along the circumference. The fastening holes 1 are formed to correspond to the fastening protrusions 22 formed in the turntable 20 (refer to FIGS. 2A and 2B). Since the section of the clamp plate 10 taken along the line A-A′ is donut-shaped, the center of the clamp plate 10 is opened.
The fastening holes 1 are formed on the circumference of the clamp plate 10. The diameter of the lower parts of the fastening holes 1 is narrower than the diameter of the upper parts of the fastening holes 1 so that the fastening protrusions 22 formed in the turntable 20 do not come out of the fastening holes 1 after the fastening protrusions 22 are assembled with the fastening holes 1.
Also, as illustrated in FIGS. 2A and 2B, the fastening protrusions 22 and an assembly groove 21 are formed in the related art turntable 20. The rotation shaft of a spindle motor (not shown) is fastened to the center of the turntable 20 so that the turntable 20 rotates in accordance with the rotation of the spindle motor.
The assembly groove 21 with which the clamp plate 10 described with reference to FIGS. 1A and 1B can be assembled is formed in the center of the turntable 20. The fastening protrusions 22 assembled with the fastening holes 1 of the clamp plate 10 are formed in the assembly groove 21.
As illustrated in FIG. 3, the clamp plate 10 is inserted into the circular assembly groove 21 formed in the turntable 20 to be combined with the assembly groove 21. At this time, the fastening protrusions 22 formed in the region of the assembly groove 21 of the turntable 20 are combined with the fastening holes 1 formed in the clamp plate 10.
At this time, in order to combine the clamp plate 10 with the turntable 20, after loading the clamp plate 10 in supersonic wave fusion equipment, the clamp plate 10 is fused in the turntable 20 to be assembled with the turntable 20.
However, when the turntable 20 and the clamp plate 10 are assembled by the supersonic wave fusion process, the following problems occur. Due to deviation in the heights of the fastening protrusions 22 formed in the turntable 20, the fusion power applied to the fastening protrusions 22 varies during the supersonic wave fusion so that defects in assembly are generated.
That is, when large fusion power is applied since the heights of the fastening protrusions 22 are high, the fastening protrusions 22 may be damaged. To the contrary, when the heights of the fastening protrusions 22 are low, the clamp plate 10 is not fastened to the turntable 20.
Also, the supersonic wave fusion equipment generates heat by the vibration of a horn with a uniform frequency to assemble the fastening protrusions 22 with the clamp plate 10. At this time, the clamp plate 10 contacts the horn to abrade and deform the horn.
The abrasion and deformation of the horn deteriorates the fusion power of the clamp plate 10 and the turntable 20. In order to prevent the fusion power of the clamp plate 10 and the turntable 20 from deteriorating, the state of the horn must be periodically examined.
On the other hand, FIGS. 4A to 4C illustrate a clip-shaped turntable and a clamp according to a related art.
As illustrated in FIGS. 4A to 4C, a clip unit 160 is formed in the related art clip-shaped turntable 150. A fastening unit 170 is formed in the clamp plate 180 corresponding to the clip unit 160. Therefore, the clamp plate 180 is fastened to the clip unit 160 of the clip-shaped turntable 150.
The center of the turntable 150 is fixed to the rotation shaft of the spindle motor. The triangular clip unit 160 is formed in the center of the turntable 150 so that the clamp plate 180 can be assembled.
As illustrated in FIG. 4C, the fastening unit 170 is formed on the top surface of the clamp plate 180. The fastening unit 170 formed in the clamp plate 180 is inserted into the clip unit 160 formed in the turntable 150 to be fastened to the clip unit 160.
That is, when the clamp plate 180 is pressed to the clip unit 160 formed in the turntable 150, the fastening unit 170 of the clamp plate 180 is inserted into the clip unit 160 to be fastened to the clip unit 160.
However, the structure in which the turntable 150 is assembled with the clamp plate 180 by the clip unit 160 has the following disadvantages. Since the clip unit 160 is formed in the body of the turntable 150 where the optical recording medium, for example, an optical disc rotates, the rotating optical disc is caught by a burr when the burr is provided in a product.
Also, when the clamp plate 180 is fastened to the turntable 150, the clip unit 160 may be deformed and noise may be generated when fastening power deteriorates due to frequent fastening operations.